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Traumatic Subarachnoid Hemorrhage


KEY FACTS

Terminology

  • Blood within subarachnoid spaces

    • Contained between pia and arachnoid membranes

Imaging

  • High density on CT, hyperintensity on FLAIR

Top Differential Diagnoses

  • Nontraumatic SAH

  • Meningitis: Cellular and proteinaceous debris

  • Carcinomatosis meningitis

  • Pseudosubarachnoid hemorrhage

  • Gadolinium administration

  • High inspired oxygen

Pathology

  • Associated with contusions, subdural or epidural hematoma, diffuse axonal injury

Clinical Issues

  • Headache, emesis, decreased consciousness

  • Trauma is most common cause of subarachnoid hemorrhage (SAH)

  • Outcome is related in logistic regression analysis to

    • Admission Glasgow Coma Scale score

    • Amount of subarachnoid blood

  • Isolated traumatic SAH, no other injuries usually benign

  • Poor prognosis if associated with other intracranial injuries

  • Vasospasm develops earlier than with aneurysmal SAH

  • Associated with ↓ neuropsychologic profiles, worse vocational outcomes in 1 year follow-up

Diagnostic Checklist

  • Isolated supratentorial sulcal blood common

  • Hyperdense blood in interpeduncular cistern may be only manifestation of subtle SAH

Coronal graphic depicts findings in a severe traumatic brain injury. Closed head trauma has resulted in multiple gyral contusions and subarachnoid hemorrhage (SAH). Most traumatic SAHs (tSAHs)
occur adjacent to parenchymal brain injuries and are found centered around the sylvian fissures, inferior frontotemporal, and convexity sulci.

Axial NECT in a patient with head trauma and tSAH demonstrates focal hyperdense collections in a few left posterior frontal sulci bordering the interhemispheric fissure
.

Axial NECT scan in a 28-year-old man with closed head injury shows tSAH in the right sylvian fissure
. Note the absence of blood in the adjacent suprasellar cistern, a more common site for aneurysmal SAH. A left parietal epidural hematoma
is also present. tSAH often occurs in combination with other injuries.

Axial NECT scan in the same patient shows the typical curvilinear configuration of tSAH
in the sulci of the right temporal lobe.

TERMINOLOGY

Abbreviations

  • Traumatic subarachnoid hemorrhage (tSAH)

Definitions

  • Blood within subarachnoid spaces

    • Contained between pia and arachnoid membranes

IMAGING

General Features

  • Best diagnostic clue

    • High density on NECT

    • Sulcal-cisternal FLAIR hyperintensity (in trauma patient)

  • Location

    • Can be focal or diffuse

      • –

        Focal SAH adjacent to contusion, subdural/epidural hematoma, fracture, laceration

        • □

          Sylvian fissure, inferior frontal subarachnoid spaces most common

        • □

          Isolated convexity sulci (adjacent to contusion)

      • –

        Diffusely in subarachnoid space &/or basal cisterns

      • –

        Layering on tentorium

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